Plastic container closure assembly

ABSTRACT

1,075,326. Seaming non-metallic sheet material. AMERICAN FLANGE &amp; MANUFACTURING CO. Inc. Jan. 20, 1966 [Feb. 8, 1965], No. 2679/66. Heading B5K. [Also in Division B8] A plastics bush 1 interiorly threaded to receive a container closure is provided with an external peripheral flange 3 and a cylindrical spigot 2, inserted into a correspondingly shaped hole 18 in the wall of a plastics container, an electrically conducting metal ring 25 lying between the two. A coil 24 is positioned adjacent the bush &amp;c. and is energized by a radio - frequency electricity generator. The current induced in the conducting ring 25 heats the latter, so that the adjacent areas of the bush 1 and the container wall become welded together, Fig. 3 (not shown). As shown before welding, the conducting ring 25 lies on a frustoconical surface 21 around the hole in the container, and adjacent a ring-shaped projection 12 between the bush flange 3 and spigot 2. In a modification, Fig. 4 (not shown), before welding the conducting ring (25) lies on a ring-shaped step (32, 33) in the container wall around the hole, and the ring-shaped projection 12, Fig. 2, around the bush 1 is omitted.

Nov. 21, 1967 J, LAURIZIO 3,353,849

PLASTIC CONTAINER CLOSURE ASSEMBLY Filed Feb. 8, 1965 ATTORNEY United States Patent 3,353,849 PLASTIC CONTAINER CLOSURE ASSEMBLY Jeremiah Laurizio, New Providence, N.J., assignor to American Flange & Manufacturing (10., Inc., a corporation of Delaware Filed Feb. 8, 1965, Ser. No. 431,069 2 Claims. (Cl. 285-21) This invention relates to container wall closure combinations and to methods for forming the same and is particularly concerned with synthetic plastic closure flanges and methods for securing the same within the openings in synthetic plastic container walls.

As the trend toward plastic materials permeates the container field at an ever increasing rate, the need for improved closure constructions and methods for applying the same becomes more and more apparent. It is advantageous and has long been the practice in a large segment of the container industry to have the container body manufactured, and frequently marketed, independently of the closure fitting which is adapted for securement and subsequent use therewith. This process requires a wall of the container to be formed with an opening therethrough and a suitable opening formation bordering the same. The fabrication of the container is then completed, either before or after filling, by securing about that opening a closure fitting such as the flange and plug type found on large containers or the nozzle and cap type more commonly used on lightweight containers. Regardless of the particular closure variant employed, there exists the problem of permanently securing the cap or plug receiving closure fitting to the container in an economical manner so as to effect a rigid leakproof engagement therewith.

In the securing of plastic fittings to plastic containers this problem becomes acute due to the inherent structural deficiencies of synthetic plastic material as compared with metal. Numerous closure arrangements enjoying various degrees of success have been advanced as possible solutions to this problem notable among which are those constructions wherein a metal sealing ring is relied upon to effect either a contraction or expansion of a portion of the closure fitting into sealing engagement with the surrounding container Wall opening formation. The snap-in type closure fitting which relies on its own resilient properties to effect a seal with the surrounding container wall has also been used with some degree of success. However, for various reasons none of these arrangements has so far provided a completely satisfactory solution to the problem.

The novel closure and method of applying the same as herein disclosed overcomes the prior art deficiencies by securing a plastic closure fitting about a plastic container wall Opening so that the resulting structure is an integral unit. In other words, through the teaching of this invention, what has heretofore been a zone of inherent structural weakness and a likely source of leakage, has been transformed into a reinforced integral part of the closure equipped container. This is accomplished by actually flowing together adjacent portions of the closure fitting and container wall into a homogeneous zone of plastic material by the use of induction welding. It has been found that induction welding produces very good results when a metallic conducting element is employed within which current is induced thus generating sufficient heat to melt the adjacent plastic surfaces and to flow them together into a homogeneous zone of juncture. There is also hereinafter disclosed an improved induction welding method of securing a novel closure fitting to a specially designed container wall opening formation. The entire closure securing operation is performed from the outside of the otherwise finished container either before or after filling the same. This novel construction and method not only produces a leakproof closure but is likewise readily adapted to high speed production practices.

3,353,849 Patented Nov. 21,- 1967 It is accordingly a primary object of this invention to improve upon closure fitting container wall combinations.

Another object is to improve upon molded plastic closure fittings for containers.

Another object is to provide an improved method of securing closure fittings to container wall openings.

A further object is to provide an improved method for induction Welding of plastic closure fittings to plastic container wall openings.

A still further object is to provide a new and improved plastic closure fitting and metal conducting ring assembly adapted for induction welding to a plastic container wall.

A more detailed object is to provide a method of induction welding a plastic closure fitting and conducting ring assembly to a plastic container wall so that a com plete and homogeneous bond is formed therebetween.

Further and more detailed objects will in part be obvious and in part be pointed out as the description of the invention taken in conjunction with the accompanying drawing proceeds.

In the drawing:

FIG. 1 is a vertical section of a closure flange and conducting ring assembly positioned about a container wall opening prior to welding in accordance with the invention;

FIG. 2 is an enlarged fragmentary vertical sectional view of the assembly of FIG. 1.

FIG. 3 is a view similar to FIG. 2 but with the assembly in welded position; and

FIG. 4 is a fragmentary sectional view of a modified form of the invention prior to the welding operation.

Considering first the closure flange per se of the inven tion as shown in FIGS. 1 and 2, the same is generally indicated by the numeral 1 and is molded from any one of a number of commonly used synthetic plastic materials. The specific form of the flange 1 includes a cylindrical neck 2 having a laterally extending circumferential shoulder 3 at the upper end thereof. The shoulder 3 is provided with a top surface 4, a peripheral outer edge wall 5 and a lower annular surface 6. The neck 2 has a cylindrical outer surface 7, a lower end 8, and a threaded interior 9 having a plug seat 10 for reception of a plug 11 as shown in- FIG. 3. At the juncture of the lower shoulder surface 6 and the outer neck surface 7 there is formed a circumferential step 12 having a cylindrical surface 13 extending downwardly at 14 from the lower shoulder surface 6 and joining at the corner 15 in a downwardly facing annular surface 16 which in turn joins the outer cylindrical neck surface 7 at 17.

The container wall 17 to which the closure flange 1 is secured is also formed of a synthetic plastic material and has an opening therethrough provided with a cylindrical surface 18 extending upwardly from the lower surface 19 of the container wall and joining at 20 a conical surface 21 which extends upwardly and outwardly joining the upper wall surface 22 at 23.

Securing of the closure flange 1 to the container wall 17 is effected by the process of induction welding Wherein a heating coil 24 is energized by a radio frequency generator so as to induce an electric current in the conducting ring 25. FIG. 2 illustrates the relationship of the closure flange 1 and conducting ring 25 to the container Wall 17 prior to the welding operation performed by the surrounding coil 24. Here it can be seen that the closure flange 1 is supported within the container wall opening by the conducting ring 25 which has an internal diameter substantially equal to the diameter of the cylindrical step surface 13. The lower shoulder surface 6 contacts the upper surface of the ring 25 and is thus held spaced above the upper wall surface 22. The ring in turn bears against the conical container wall surface 21 adjacent the upper end 23 thereof. This temporary seating 3 of the closure flange and conducting ring upon the conical surface 21 properly centers the flange neck 2 within the container wall opening surface 8, the space therebetween being enlarged for purposes of illustration and indicated by numeral 26 in FIG. 3. The induction heating coil 24 is here shown as a ring of copper tubing which surrounds the conducting ring 25 in operative relationship thereto.

Upon initiation of the welding cycle the conducting ring 25 is heated well beyond the melting point of the plastic material causing the ring to partially embed itself in both the lower shoulder 6 and the conical flange surface 21. The flange 1 accordingly settles downwardly within the container wall opening due to the melting away of the opposing surfaces above and beneath the ring 25. As the flange drops or settles, a slight downward force on top of the flange may be used to assist in this movement. The step formation 12 also melts commencing with the cylindrical surface 13 which initially lies in contact with the ring 25. The plastic material thus melted flows into and fills the pocket formed above the lower end of the conical surface 21 and in addition, flows down into the space 26. Upon completion of the welding cycle the flange lower shoulder surface 6 contacts the upper container wall surface 22 with the lower end 8 of the flange neck in alignment with the lower container wall surface 19. At the completion of the welding cycle as illustrated in FIG. 3, there is an uninterrupted zone of fusion between the flange and container wall extending from a point indicated at 27 along the juncture of the flange shoulder and container wall to a point 28 along the vertical annular space 26. This fusion zone in effect creates an integral flange container wall construction possessing all the inherent advantages thereof. More specifically, the connection hereby formed may be subjected to internal pressures limited only by the strength of the container wall itself. Similarly, resistance to rotational torque between the flange and container wall is also limited only by the shear strength of the container wall material. Furthermore, any damaging differential shrinking or swelling of the respective parts is eliminated.

Here it should be noted that good fusion results when the same plastic material is used in both the flange and the container wall. Polyethylene or polypropylene are nonlimiting examples of well-known molding plastics which could be employed. It has also been found in this regard that it is advantageous to-employ not only the same plastic in the molding of both the flange and the container wall, but that the plastic in both elements have substantially the same melting point. These factors contribute toward achieving an uninterrupted homogeneous bond between the respective parts.

A modified form of the invention is shown in FIG. 4 comprising a container wall section 30 and a flange member 31. In this form of the invention the relationship between the metal conducting ring 25 and the heating coil 24 is substantially the same as in the preferred form, however, here the container wall opening is bordered by a step having a vertical wall 32 and a horizontal annular step surface 33. The ring 25 is thus between the annular step surface 33 and the under surface 34 of the flange shoulder 35. In the securing or welding operation, the

4i plastic material in the immediate area melts, causing the flange 31 to move downwardly within the container wall opening until the lower shoulder surface 34 contacts the upper surface 36 of the container wall.

Though in the foregoing the preferred and one modified form of closure flange and combination and the presently preferred method of securing the flange within the container wall opening have been disclosed and since one skilled in the art might well modify the structures or method without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In container wall closure member assembly, a container wall molded of synthetic plastic material formed with an opening therethrough, a closure flange molded of synthetic plastic material comprising an interiorly threaded cylindrical neck terminating at one end in a circumferentially enlarged shoulder said shoulder having a flat upper surface, a lower annular surface and an outer edge, an annular projection at the juncture of said lower shoulder surface and said cylindrical neck, a metal conducting ring surrounding said flange neck and engaging said lower shoulder surface and said annular projection.

2. In container wall closure member combinations, a closure member molded of synthetic plastic material comprising a cylindrical neck terminating at one end in a circumferentially enlarged shoulder, said shoulder having a flat upper surface,, a lower annular surface and an outer edge, a right angled annular step at the juncture of said lower shoulder surface and said cylindrical neck, and a metal conducting ring surrounding said flange neck and engaging said lower shoulder surface and the radially outwardly facing wall of said step.

References Cited UNITED STATES PATENTS 2,305,197 12/ 1942 Sheridan. 2,642,911 6/1953 DeShazor 285-21 X 2,837,360 6/1958 Ladd. 2,887,244 5/1959 Betner 220-39 X 2,958,546 11/1960 Lee 28521 2,992,838 7/1961 Wallace 285-21 3,052,926 9/1962 Quinche et al 264-248 3,086,679 4/1963 Bijvoet 22039 X 3,172,933 3/1965 Flax 264-248 FOREIGN PATENTS 1,261,896 4/1961 France.

928,338 6/1963 Great Britain.

605,072 5/ 1960 Italy.

EDWARD C. ALLEN, Primary Examiner.

THOMAS P. CALLAGHAN, CARL W. TOMLIN,

Examiners. T. A. LISLE, Assistant Examiner. 

1. IN CONTAINER WALL CLOSURE MEMBER ASSEMBLY, A CONTAINER WALL MOLDED OF SYNTHETIC PLASTIC MATERIAL FORMED WITH AN OPENING THERETHROUGH, A CLOSURE FLANGE MOLDED OF SYNTHETIC PLASTIC MATERIAL COMPRISING AN INTERIORLY THREADED CYLINDRICAL NECK TERMINATING AT ONE END IN A CIRCUMFERENTIALLY ENLARGED SHOULDER SAID SHOULDER HAVING A FLAT UPPER SURFACE, A LOWER ANNULAR SURFACE AND AN OUTER EDGE, AN ANNULAR PROJECTION AT THE JUNCTURE OF SAID LOWER SHOULDER SURFACE AND SAID CYLINDRICAL NECK, A METAL CONDUCTING RING SURROUNDING SAID FLANGE NECK AND ENGAGING SAID LOWER SHOULDER SURFACE AND SAID ANNULAR PROJECTION. 